We've seen whenever we attend meeting through teams, while attending teams and outlook profile went on busy mode automatically and when meetings ends it again switch to online. But sometime it gets stuck on busy mode or offline and doesn't change to online due to this while adding that person in a meeting always shows that he is not available.
Real time presence updated are coming to teams over the next few months so this will probably be fixed with this update. Give it some time and I think this issue will go away. The real-time presence is listed on the office 365 roadmap if you want to keep track of deployment.